This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Alcoholism and alcohol abuse are significant public concerns, leading to fetal alcohol syndrome, liver cirrhosis and aerodigestive cancers. It is hypothesized that one mechanism by which alcoholism leads to these diseases is via disruption of homeostasis of the potent cell-signaling molecule, retinoic acid. Currently there is no comprehensive model of retinol-related pathways, nor their dysregulation in liver disease. As a consequence there is considerable debate about which enzymes on the pathway of retinol to retinoic acid are significant in vivo and which are affected by ethanol or its metabolites, and to what degree. We hypothesize that the ethanol-induced increases in NADH and acetaldehyde (Ach) significantly inhibit retinoic acid synthesis in human liver cells by inhibition of aldehyde and alcohol dehydrogenases. In specific Aim 1 we will computationally model the effect of ethanol-induced changes in NADH and Ach on retinol oxidation by ADH isoforms. In Specific Aim 2 we will measure in vitro retinol oxidation kinetics of recADH1 and 7 isoforms, in the presence of Ach and NADH levels to match the computational parameters. In Specific Aim 3 we will assess the impact of elevated NADH and Ach on retinol oxidation by HeLa-ADH1B, and HeLa-ADH1B-ALDH2 cells. Finally, in Specific Aim 4 we will design a computational model of the retinol metabolic pathways present in human hepatic stellate cells. Results from these studies will enable us to develop a better model for the role of the cell-signaling model retinoic acid in normal liver function and its disruption in alcohol-related disease.